Re: [PATCHv2] perf probe: Fix failure to add multiple probes without debuginfo
From: Masami Hiramatsu
Date: Fri Mar 20 2015 - 03:43:00 EST
(2015/03/20 10:56), He Kuang wrote:
> Perf tries to find probe function addresses from map when debuginfo
> could not be found.
>
> To the first added function, the value of ref_reloc_sym was set in
> maps__set_kallsyms_ref_reloc_sym() and can be obtained from
> host_machine->kmaps->maps. After that, new maps are added to
> host_machine->kmaps->maps in dso__load_kcore(), all these new added maps
> do not have a valid ref_reloc_sym.
>
> When adding a second function, get_target_map() may get a map without
> valid ref_reloc_sym, and raise the error "Relocated base symbol is not
> found".
>
> Fix this by using kernel_get_ref_reloc_sym() to get ref_reloc_sym.
>
> This problem can be reproduced as following:
>
> $ perf probe --add='sys_write' --add='sys_open'
> Relocated base symbol is not found!
> Error: Failed to add events.
>
> After this patch:
>
> $ perf probe --add='sys_write' --add='sys_open'
> Added new event:
> probe:sys_write (on sys_write)
>
> You can now use it in all perf tools, such as:
>
> perf record -e probe:sys_write -aR sleep 1
>
> Added new event:
> probe:sys_open (on sys_open)
>
> You can now use it in all perf tools, such as:
>
> perf record -e probe:sys_open -aR sleep 1
>
OK, I've checked that this solve the problem :)
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Thank you!
> Signed-off-by: He Kuang <hekuang@xxxxxxxxxx>
> ---
> tools/perf/util/probe-event.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
> index c5e1338..c1ccd6a 100644
> --- a/tools/perf/util/probe-event.c
> +++ b/tools/perf/util/probe-event.c
> @@ -2507,7 +2507,6 @@ static int find_probe_trace_events_from_map(struct perf_probe_event *pev,
> int max_tevs, const char *target)
> {
> struct map *map = NULL;
> - struct kmap *kmap = NULL;
> struct ref_reloc_sym *reloc_sym = NULL;
> struct symbol *sym;
> struct probe_trace_event *tev;
> @@ -2540,8 +2539,7 @@ static int find_probe_trace_events_from_map(struct perf_probe_event *pev,
> }
>
> if (!pev->uprobes && !pp->retprobe) {
> - kmap = map__kmap(map);
> - reloc_sym = kmap->ref_reloc_sym;
> + reloc_sym = kernel_get_ref_reloc_sym();
> if (!reloc_sym) {
> pr_warning("Relocated base symbol is not found!\n");
> ret = -EINVAL;
>
--
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Research Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@xxxxxxxxxxx
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